Yamagishi, Yoshino, Iida, and Niiyama are a group of four close friends. Yamagishi has secretly loved Iida for a long time but has never confessed. Yoshino is always cheerful, especially interested in sexual matters. One day, while Yoshino was bragging to Yamagishi about a new dildo she had bought, Niiyama and Iida overheard. Out of curiosity, she demanded to go to Yoshino's house to see it. Curious about how to use the dildo, Niiyama asked Yoshino to use it in front of her for observation. However, Yoshino was at a loss, as his penis remained flaccid. Yoshino then tried to ask Niiyama to show his underwear for masturbation, but unexpectedly, Niiyama immediately complied! And then both gradually progressed to sexual activity, right in front of Iida and Yamagishi. The two just stood silently watching their close friends have sex in front of them. But after Niiyama finished, Yoshino called Iida. Yamagishi thought that Iida would refuse, believing she would never do this out of curiosity. He thought so until Yoshino pushed his penis deep into Iida's vagina...